Algae

In the life cycle of the lake it is expected that there will be Algae blooms at various times of the year, which is why swimming is not recommended. But it does seem like the Algae has been a lot worse lately. The Northern corner of the lake has a beautiful mini cove. Very smelly algae has been pushed up into the cove in the last few months. It is a common belief amongst the local folk that if the third fountain was reactivated the water would be oxygenated and moved around enough to prevent this from happening.

The other thing that is a real problem in contributing to Algae growth is the use of Phosphate fertilizers on lawns and gardens surrounding the lake. See Lawn Fertilisers

Freshwater algal blooms are the result of an excess of nutrients, particularly some phosphates. The excess of nutrients may originate from fertilizers that are applied to land for agricultural or recreational purposes. They may also originate from household cleaning products containing phosphorus. These nutrients can then enter watersheds through water runoff. Excess carbon and nitrogen have also been suspected as causes. Presence of residual sodium carbonate acts as catalyst for the algae to bloom by providing dissolved carbon dioxide for enhanced photo synthesis in the presence of nutrients.

When phosphates are introduced into water systems, higher concentrations cause increased growth of algae and plants. Algae tend to grow very quickly under high nutrient availability, but each alga is short-lived, and the result is a high concentration of dead organic matter which starts to decay. The decay process consumes dissolved oxygen in the water, resulting in hypoxic conditions (low oxygen). Without sufficient dissolved oxygen in the water, animals and plants may die off in large numbers.

Blooms may be observed in freshwater aquariums when fish are overfed and excess nutrients are not absorbed by plants. These are generally harmful for fish, and the situation can be corrected by changing the water in the tank and then reducing the amount of food given.

Download a PDF of Algal Blooms by the WATER AND RIVERS COMMISSION JULY 1998 More on Algae Blooms &  Eutrophication